This is a multicenter, open-label, dose-escalation and backfill, and cohort-expansion phase I clinical study to evaluate the safety, tolerability, pharmacokinetics, immunogenicity, and preliminary antitumor efficacy of SYS6051 in participants with advanced solid tumors.

Inclusion Criteria:

1. Fully understand the clinical study and voluntarily sign the written ICF;
2. Age ≥ 18 years;
3. Have at least one measurable lesion according to RECIST 1.1;
4. ECOG performance status score of 0 to 1;
5. Have adequate organ function;
6. Expected survival of at least 3 months;
7. Eligible participants of childbearing potential must agree to use a reliable method of contraception with their partner during the study and for at least 4 months (males) or 7 months (females) after the last dose. Female participants of childbearing potential must have a negative blood pregnancy test within 7 days prior to the first dose;
8. Histologically or cytologically confirmed diagnosis of advanced solid tumors. -

Exclusion Criteria:

1. Presence of high bleeding risk factors; 2. Presence of active ocular disease; 3. Patients with other active malignant tumors; 4. Uncontrolled serous effusions requiring frequent drainage or medical intervention within 14 days prior to the first dose; 5. Serious chronic or active infection; 6. Surgical on vital organs within 4 weeks prior to the first dose or planned systemic or local tumor resection during the study; 7. Untreated (including baseline findings) or unstable parenchymal metastases, spinal cord metastases or compression, carcinomatous meningitis; 8. History of non-infectious lung disease/pneumonitis requiring steroid hormone therapy or current interstitial lung disease/pneumonitis or suspected by imaging during screening; 9. History of significant cardiovascular disease; 10. History of immunodeficiency, Active hepatitis B or hepatitis C; 11. Known serious allergic reactions to the study drug or other ingredients and excipients in the formulation; 12. Pregnant or lactating women; 13. Presence of other conditions that could interfere with the participant 's participation in study procedures or would not be in the best interest of the participant' s participation in the study or affect the study results: such as a history of mental illness, drug use, or drug abuse, any other clinically significant disease or condition.

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